Published on International Journal of Biology, Physics & Mathematics
Publication Date: August, 2019
Saddam Husain Dhobi, Ram Chandra Pangeni, Kishori Yadav & M. D. Jahangeer Rangrej
Science and Techonology, Tribhuvan University (Physics), Kathmandu, Province-3, Nepal
The main work of this research work is to calculate voltage generated by incidence of red photon on the surface atoms of poly crystalline silicon base solar panel. This is calculated by passing red leaser photon through aluminum pinhole of different diameters and then incidence on the solar panel pinhole whose surfaces closed by highly absorption materials i.e. whole panel is cover except the pinhole of desire diameter. On taking the different data i.e. voltage vs incidence photon through pinhole we find that on decrease the diameters of pinhole of aluminum plate for fixed pinhole of solar panel the voltage also decrease and vice-versa. On the other hand, we also calculate voltage generated by the number of atoms on which photon incidence in certain cross-section area. These data are listed on observation table1 and with the help of these data we are able to calculated the average cross-section area of red photon.
Keywords: Aluminium Pinhole, Poly Crysatlline Silicion, Photon, Cross-section area, Red Photon.
The phenomena which is used to find the voltage across the atoms or voltage generate by atom when photon is incidence it. When photon incidence on the surface of atoms it ejected electron from the atom after distribution of photon energy. In this experiment, photon energy are able to ejected the electron from the atom which is bounded or correlated with other atoms. This phenomena can also called photoelectric effect.
In this work we are trying to introduce the the energy lose or distribution by a single photon energy which are unable to eject the electron from the atom is divided into numbers of packet energy. Due to the division of these numbers of packet energy of single photon, the work function is greater then theses packet energy generated by single incidence photon. This phenomena is only seen when photon is incidence on an atom expect normally i.e. the division of single photon is only experience when photon is incidence with certain angle expect perpendicular.
This is observed when we focus for the perpendicular incidence the photon on the pinhole of solar panel. Because during the focusing for perpendicular incidence of photon on the solar panel considerable surface the voltage obtained from multi meter is less than voltage obtained at perpendicular incidence of photon on considerable surface.
Figure 1: Sketch of different component of solar panel and circuit connection to obtained Voltage.
Some part of our experiment contain this whole system of figure 1. and more extra are design to obtained the data which is shown in experimental set up. The short description of different component of solar panel are given below:
1.2 Electrons & Hole: An intrinsic or pure silicon crystal at room temperature has sufficient heat or thermal energy for some valence electrons to jump the gap from the valence band into the conduction band and hence becoming free electrons. These free electrons are called conduction electrons. When an electron jumps to conduction band, a vacancy is left in valence band within silicon crystal. These vacancy is called a hole. For every electron raised to the conduction band by external energy, there is one hole left in the valence band, creating what is called an electron-hole pair. Recombination occurs when a conduction-band electron loses energy and falls back into a hole in the valence band
.3 Depletion Layer: The free electrons in the n-region are randomly drifting in all directions. At the instant of the pn junction formation, the free electrons near the junction in the n region begin to diffuse across the junction into the p region where they combine with holes near the junction. When pn junction is formed, the n region loses free electrons as they diffuse across the junction. This creates a layer of positive charges near the junction. As the electrons move across the junction, the p region loses holes as the electrons and holes combine, which creates a layer of negative charges near the junction. These two layers of positive and negative charges form the depletion region. As electrons continue to diffuse across the junction, more and more positive and negative charges are created near the junction as the depletion region is formed. A point is reached where the total negative charge in the depletion region repels any further diffusion of electrons into the p region and the diffusion stops. In other words, the depletion region acts as a barrier to the further movement of electrons across the junction.
1.4 N-type Silicon: To increase the number of conduction-band electrons in intrinsic silicon, pentavalent impurity atoms are added. These are atoms with five valence electrons such as arsenic, phosphorus (P), bismuth (Bi), and antimony (Sb). Each pentavalent atom forms covalent bonds with four adjacent silicon atoms. Four of the antimony atom’s valence electrons are used to form the covalent bonds with silicon atoms, leaving one extra electron. A conduction electron created by this doping process does not leave a hole in the valence band because it is in excess of the number required to fill the valence band. The electrons are called the majority carriers in n-type material. Holes in an n-type material are called minority carriers.
1.5 P-type Silicon: To increase the number of holes in intrinsic silicon, trivalent impurity atoms are added. These are atoms with three valence electrons such as boron, indium, and gallium. Each trivalent atom forms covalent bonds with four adjacent silicon atoms. All three of the boron atom’s valence electrons are used in the covalent bonds. Because the trivalent atom can take an electron, it is often referred to as an acceptor atom. The number of holes can be carefully controlled by the number of trivalent impurity atoms added to the silicon. A hole created by this doping process is not accompanied by a conduction electron. The holes are the majority carriers in p-type material. Conduction-band electrons in p-type material are the minority carriers.
1.6 Anti Reflection Coating: To reduces the reflection of light from the surface of the solar cell, to further reduce the reflection of incoming radiation from sun in order to maximize the absorption of light, a silicon nitride film (SiNx) or other such properties material, which acts as Anti reflection coating, is deposited by plasma enhanced chemical vapor deposition or any other method on the front surface of the solar cell. This film serves as a passivating layer for the front surface of the solar cell in addition to serving as an anti-reflection coating. This film must be optimized to absorb the majority of incoming radiation as well as passivate the surface satisfactorily. The target thickness of anti refelcting coating for baseline cells is set at 780nm1.
1.7 Metallic conducting Strips: Continuous efforts to develop new materials and modeling techniques for solar cells are being made in order to produce new photovoltaic devices with improved electrical performances. In addition to the new semi conducting materials, solar cells consist of a top metallic grid or other electrical contact to collect electrons from the semiconductor and transfer them to the external load. In a solar cell operating under the normal conditions, even a small deviation from the optimum power condition can cause a loss of conversion efficiency2.
The rays of light neither mutually color each other, nor mutually illuminate each other, nor mutually impede each other in any way. This is just like one physical motion’s not impeding another as study by Kepler and first observe the scattering of photons by photons in an experiment seems to have been undertaken in 1928 in the Soviet Union by S. I. Vavilov. In the experiment, no experimental sign of photon-photon collisions was found and Hughes and Jauncey give as bound for the cross section.
When light and sound simultaneously pass through a medium, the acoustic phonons of the sound wave scatter the photons of the light beam. This scattering of light from acoustic modes is called Brillouin scattering. A particularly interesting effect of Brillouin scattering has to do with the frequency of the scattered light. An incident photon can be converted into a scattered photon of slightly lower energy, normally’ propagating in the backward direction, and a phonon. For a Stokes process, where a phonon is generated, the frequency of the scattered light is decreased; for an anti-Stokes process, where a phonon is annihilated, the frequency of the scatted light is increased. Increased frequency, by the equation E = hv, means increased photon energy. The difference between the energy of the scattered photon and the incident photon is called the Brillouin shift4.
QED is normally used to describe the scattering of electrons. It is recognized in QED, the quantum mechanical formalism describing the scattering of photons would be different than the scattering of electrons as the cross sections for scattering or their interaction coefficients with the lattice would be different. In describing diffraction consistent with the conventions of QED, we adopt a momentum representation for the Coulomb potential associated with the lattice. The most probable values for the magnitude of the y-momentum of the virtual photons associated with the scattering potential are integral multiples of h/2d. On recognize these energies are the eigenvalues of the photon standing wave eigenfunctions for the particle-in-a-box problem in quantum mechanics where the length of the box is d. The scattering probability distribution observed with photon diffraction is derived from a function of the y-momentum exchanged from the scattering by virtual photons of the lattice summed over the probabilities or densities of the virtual photons with the different momentum values5.
Comparing spectra, the Brillouin shift is much smaller than the Raman shift because the velocity of acoustic waves is much less than the velocity of light. This was already known from the spectrum of spontaneous scattering, where the Raman process gives a much larger shift than Brillouin scattering. Parametric processes require conservation of both energy and momentum. Stimulated Brillouin scattering occurs when a beam of laser light generates a parametric process that simultaneously produces an exactly retrorefected Stokes beam and an acoustic wave traveling in the forward direction. Energy conservation requires that the Stokes beam frequency is reduced from the laser frequency by the frequency of the acoustic wave. Historically the term “Stokes was named for Sir George Gabriel Stokes, who in 1852 described the change in wavelength of fuorescence, which is always at lower photon energy than the incident light. When Raman scattering was discovered, similar shift to lower photon energy was called Stokes light. When Raman scattering was discovered to have weak signals at shorter wavelength than the incident light, this was called “anti-Stokes” light6.
One or several scattering processed Rayleigh scattering, Brillouin scattering, and Raman scattering, can occur due to the interaction of an incident wave with a medium. When the intensity of light is low the resulting scattering process will be spontaneous. However, when the incident intensity reaches a certain threshold, stimulated scattering will be observed with a strong interaction between light fields and matter. In Brillouin scattering is both stimulated and spontaneous, a pump photon at a frequency up produces an acoustic phonon and a red-shifted. The energy and momentum conservation requirements on Stokes and anti-Stokes Brillouin scattering are as follows. Slow light, the propagation of an optical pulse at a very low group velocity, is of interest for enhancing the interaction of light and material and to provide higher controllability of the gain spectrum bandwidth. SBS has been studied in a variety of gas, liquid, and solid media for different applications, and SBS capabilities vary greatly depending on the choice of gain medium. Thus overall potential for SBS applications is broad, selection of the right gain material for a particular application is critical. In practice, many more parameters need to be taken into consideration when selecting a medium, including the transmittance at the wavelength of interest, gain coefficient, generation and damage threshold, Brillouin frequency shift and line width, environmental sensitivity, toxicity, as well as available size7.
The molecular theory of matter starts with quantum mechanics and statistical mechanics. According to the quantum mechanical Heisenberg Uncertainty Principle, the position and momentum of an object cannot be determined simultaneously and precisely. The Heisenberg Uncertainty Principle helps determine the size of electron clouds, and hence the size of atoms. Heisenberg’s Uncertainty Principle applies only to the subatomic particles like electron, positron, photon, etc. It does not forbid the possibility of nanotechnology, which has to do with the position and momentum of such large particles like atoms and molecules. This is because the mass of the atoms and molecules is quite large, and the quantum mechanical calculation by the Heisenberg Uncertainty Principle places no limit on how well atoms and molecules can be held in place8. The atomic radius is taken as half of the inter atomic distance in a crystalline state. The atomic radius of elements and the relationship with their position in the periodic table, together with the numerical values of atomic radius9.